Image processor,its image reader and fiber lens,and method of manufacturing fiber lens

ABSTRACT

An image reader for reading an image drawn on a paper or a sheet-like recording medium, an image processor provided with the image reader, such as a copying machine, a scanner and the like, and a fiber lens to be applied to those devices. The image processor has to be large in the whole size of device to read both sides of an original. Therefore, the image processor of the present invention comprises an image reader ( 10   a ) on the upper side of transport path and an image reader ( 10   b ) on the lower side of that respectively. In order to downsize the device, it is necessary to shorten the diameter of optical fiber ( 140 ) of the fiber lens ( 14 ) installed in the imager reader as light receiving means. In this case, the optical fiber ( 140 ) is provided with a light-absorbing layer  8  ( 143 ) around of the optical fiber ( 140 ) in order to restrain the crosstalk and the flare phenomenon. The illuminance of light source means ( 15 ) installed in the image reader gets smaller as the device is downsized. In case where the illuminance is small, the image quality is deteriorated by the floating of the original. Accordingly, the image reader should be provided with the light source means so as to uniform the illuminance over a specific width of the main and sub scanning directions. Therefore, it is possible to avoid the deterioration of the image quality.

TECHNICAL FIELD

[0001] The invention relates to an image reader for reading images drawnon a paper or a sheet-like recording medium, a fiber lens, the method ofmanufacturing the fiber lens, and an image processor provided with theimage reader.

BACKGROUND ART

[0002] The image processor is represented as the multi-functionalprinter combining respective functions of a copying machine, a scanner,a printer, and a facsimile, or respective functions of a facsimile and acopying machine and a printer. Such image processor comprises an imagereader for reading images such as shapes and positions of characters andgraphic patterns drawn on a paper or a sheet-like recording medium(which is called an original hereafter).

[0003]FIG. 15 shows an example of the image reader applied to thecopying machine.

[0004] First, an original 117 placed on an original tray 118 comprisingan original carrier 101 is drawn into a machine casing by a pickingroller 119, and then fed to a read station 106 by an upper and lowerfeeding rollers 102 a and 102 b. The original 117 fed to the readstation 106 in this way is carried forwarder by a belt roller 103 placedon the upper side of a transport path 114 of the original.

[0005] At a reading position P of the read station 106, the images drawnon one side of the original 117 is read out. After completing thereading, the belt roller 103 carries the original 117 from the readstation 106 to a reversing roller 104. After the reversing roller 104makes the original 117 turn over, the original 117 is carried to theread station 106 again by the belt roller 103 of which the rotationdirection is reversed. The read station 106 reads the images drawn onthe other side of the original 117, and then the original is dischargedoutside of the copying machine.

[0006] The read station 106 is provided with an image reader in whichthe original 117 is irradiated with the light from a light source 112like a fluorescent light at the reading position P, and then thereflected light is guided to a lens 109 through a mirror 113 and isfocused on a sensor 108 like CCD.

[0007] Though in the above description the light source without movingitself is to read the original 117 moving in the transport path 114,there is an other configuration: the glass original table (not shown inthe drawing) is provided at the position below the transport path 114,and the original placed on this original table is read out by moving thelight source 112 (the reading position P as well as the light source112). Such configuration is available for obtaining image data from theoriginal that cannot be inserted into the original tray 118, such as abook, for example.

[0008]FIG. 16 is a diagram showing an example of related arts of theimage reader different from the above-mentioned one. As shown in FIG.16, the image reader is a contact type comprising light receiving means126 provided with a lens using a rod lens array 121 and a sensor 108using CCD or the like, in addition to the light source 112 of LED arrayand etc.

[0009] The LED array used as the light source 112 is configured bydisposing a plurality of LED element 125 at specific intervals on oneside of a basal plates 124 as shown in FIG. 17, for example.

[0010] On the light source 112, the each LED array is placedsymmetrically so that the illuminance of the light of the LED array mayreach the peak at the reading position P of the original 117.

[0011] The rod lens array 121 is placed above the reading position P ofthe original 117. The rod lens array 121 is configured as shown in FIG.18: a specific number of rod lens 122, which is in a specific length andin a cylindrical shape of a specific diameter, may be disposed in aplurality of line so as to adjoin to each other. And such configured rodlens 122 is put between basal plates 124 through a black resin used as alight-absorbing layer 123 for removing the light noises of the crosstalkand the flared light.

[0012] At this time, as the angular aperture that is an angle betweenthe central axis of the rod lens 122 and the light incident on the rodlens 122 gets smaller, the focal depth of the incident light becomesdeeper. When the focal depth becomes deep, it is possible to obtain aclear picture within a specific area from the focus of the rod lens 122as much as the one at the focus position. It is equivalent to theimprovement of the image quality. In other words, in order to improvethe image quality, it is necessary to narrow the angular aperture. Toachieve this object, the rod lens 122 may be small in the outsidediameter of circle.

[0013] The crosstalk is a phenomenon that in case where the reflectedlight on the original 117 is incident to the central axis of the rodlens 122 of the rod lens array 121 over specific angles, the reflectedlight is not reflected on the side surface of the cylinder of the rodlens 122 but penetrates into the other adjacent rod lens. Accordingly,the reflected light does not converge on a position to be converged, butis detected as the noises by the sensor 108.

[0014] The flared light is the irregular reflection of light on theoriginal 171, and the phenomenon exerts the bad influence upon thepositions other than that to be converged. It is also detected as thenoises by the sensor 108.

[0015] The sensor 108 is CCD, CMOS (Complementary Metal OxideSemiconductor), or the like, for example. It is needless to say that itis placed on the opposite side to the original of the rod lens array121.

[0016] One of the demerits of the conventional image processor like theabove copying machine is that the device becomes big in size because thecopying machine must be provided with the reversing roller 104 due toreading the original 117 per one side. In addition, there are otherdemerits that the rotation direction of the belt roller 103 must becontrolled so as to reverse the rotation direction corresponding to thereading surface of the original 117 and it takes long time for thereading.

[0017] If the contact type of image reader is adopted, it is possible todownsize the image processor further more than a case of adopting theimage reader using the mirror and lens. Even in the contact type ofimage reader, the optical path length requires approximately 50 mm byadopting the rod lens 122 in 0.6 mm diameter.

[0018] The diameter of the rod lens 122 used for the light receivingmeans 126 may be small in order to shorten the focal length (shorten theoptical path length) of the contact type of image reader. However, thesmaller the diameter of the rod lens 122 becomes, the more conspicuousthe crosstalk and the flare phenomenon becomes. It makes impossible toobtain clear images.

[0019]FIGS. 19A and 19B are graphs showing the distribution of theilluminance of the conventional image reader provided with the LED arrayas the light source 112. In case where the reading direction is the subscanning direction as described previously, if the illuminance isdistributed around the irradiated position so as to form a peaked shape,the distribution of the illuminance on the original 117 when it ispositioned at the reading position P can be shown as in FIG. 19A. On theother hand, under a state where the original 117 shifts in the directionaway from the light source 112 at the reading position P, thedistribution of illuminance is shown in FIG. 19B.

[0020] That is to say, the position away from the peak of thedistribution of illuminance becomes the reading position P, accordinglywhile keeping the illuminance small the reading is performed. In casewhere the fluorescent light is used as the light source 112 as describedabove, the light intensity is strong originally. And the illuminationwidth is wide, so that the influence on the image quality at the copyingis less even when the original shifts more or less. However, in order todownsize the image reader, LED and the electronic luminescence used asthe light source has a comparative small light intensity, and the lightwith narrow illumination width must be used.

[0021] If the device works on the basis of the above-mentioneddistribution of illuminance in this case, it is not possible to obtainthe sufficient image quality.

[0022] It is noted that when the image reader reads the images drawn onthe original 117, the direction that the original is read at a time atthe reading position P is the main scanning direction, the directionthat the original is read one after another corresponding to thecarrying direction of the original is the sub-scanning direction.

[0023] The invention is proposed considering the above-mentionedconditions, and has an object to provide the image processor capable ofdownsizing the image reader, shortening the time for reading the imagesdrawn on the both sides of the original, and avoiding the deteriorationof image quality accompanying with the downsizing, the image reader andthe fiber lens thereof, and the method of manufacturing the fiber lens.

DISCLOSURE OF INVENTION

[0024] In order to achieve the above object, the invention comprisesimage readers provided on both the upper and lower sides of thetransport path of the original for reading images drawn on the bothsides of the original. In this case, the image readers on the upper andlower sides are arranged so as to differ positions irradiated with lightby the upper and lower light sources.

[0025] In addition, the image readers on the upper and lower sides arefixed at specific positions respectively; otherwise the image reader onthe upper side is fixed at a specific position, while the other on thelower side is movable.

[0026] Moreover, the invention may comprise reading correction means forcorrecting the reading characteristics of the image readers on the upperand lower sides so as to be the same.

[0027] A fiber lens installed in the image reader comprises alight-absorbing layer around at least one of individual optical fibersof a specific length disposed in a specific shape and a fiber-bundlebundling a plurality of the optical fibers. The fiber lens may bemanufactured by stuffing a specific shaped frame opening top and bottomends with one of individual optical fibers and a fiber bundle bundling aplurality of the optical fibers around which a light-absorbing layer isformed, with a longitudinal direction of the optical fiber in thevertical direction and side by side in a diametrical direction of theoptical fiber, and then solidifying an adhesive filling a gaps of theoptical fibers.

[0028] The light source means of the invention is configured that acondensing lens in a specific shape and with a specific refractive indexbe attached to an irradiating surface of a belt-like light source, inorder to uniform the illuminance over the specific width of themain-scanning and the sub-scanning directions for reading images on theoriginal surface.

[0029] The shape of the condensing lens is preferable that a plane or aconcave is placed at a position corresponding to the top of the curvedsurface of a cylinder of which cross sectional view is in D-shape.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]FIG. 1 is a block diagram of a copying machine of this inventionperforming the both-sides reading:

[0031]FIG. 2 is a block diagram of an image reader of this invention:

[0032]FIG. 3 is a perspective view of a fiber lens installed in an imagereader of this invention:

[0033]FIG. 4 is a perspective view of the other fiber lens installed inan image reader of this invention:

[0034]FIG. 5 is a perspective view of an optical fiber comprising thefiber lens of this invention:

[0035]FIG. 6 is a sectional view taken along line A-A′ of the fiber lensof this invention:

[0036]FIG. 7 is a perspective view of a light source installed in theimage reader of this invention:

[0037]FIG. 8 is a diagram showing an example of the correcting on thebasis of γ-value of the reading correction means of this invention:

[0038]FIG. 9 is a perspective view of the light source means installedin the image reader of this invention:

[0039]FIG. 10 is a graph showing the distribution of illuminance by thelight source means installed in the image reader of this invention:

[0040]FIG. 11 is a perspective view showing a configuration of the lightsource means installed in the image reader of this invention:

[0041]FIG. 12 is a perspective view showing a configuration forobtaining color light source by the light source means installed in theimage reader of this invention:

[0042]FIG. 13 is a diagram showing a concrete configuration of acondensing lens installed in the light receiving means of the imagereader of this invention:

[0043]FIG. 14 is a graph showing the distribution of illuminance of thecondensing lens shown in FIG. 13:

[0044]FIG. 15 is a block diagram of a conventional copying machineperforming the both-sides reading:

[0045]FIG. 16 is a block diagram of a conventional contact type of imagereader:

[0046]FIG. 17 is a perspective view of a light source of a conventionalcontact type of image reader:

[0047]FIG. 18 is a perspective view of a rod lens array installed in aconventional contact type of image reader: and

[0048]FIG. 19 is a graph showing the distribution of illuminance of alight source of a conventional contact type of image reader.

BEST MODE FOR CARRYING OUT THE INVENTION

[0049] The invention is described according to FIGS. 1 to 14.

[0050]FIG. 1 shows a configuration of a copying machine employing animage reader of the present invention.

[0051] Like the related art, an original 9, which is fed into the insideof the copying machine by a picking roller 31 constituting an originalcarrier 2, is sent to a horizontal transport path 13 by upper and lowerfeeding rollers 32 a and 32 b. On the transport path 13, a belt roller 4for receiving the original 9 from the feeding rollers 32 a and 32 b andsending it forwarder is placed. The belt roller 4 is controlled so as tostart up when the tip of the original 9 reaches a specific position.

[0052] It is around the front end of the horizontal transport path 13that two image readers 10 a and 10 b are provided above and below. Theboth sides of the original 9 are arranged to be read simultaneously atthe upper and lower reading position Pa and Pb when the original 9 iscarried through.

[0053] As above, in case of reading images on the both sides of theoriginal 9, if it is arranged that the respective light source meansinstalled in the upper and lower image reader 10 a and 10 b irradiatelight on the same position of the upper and lower sides of the original,the irradiation light interferes mutually. In order to avoid suchinterference, the positions of respective image readers 10 a and 10 aredifferent so that each light source means in the image reader 10 a and10 b may not irradiate light on the same position above and below.

[0054] In addition, the image reader 10 a and 10 b involve the readingcharacteristics such as γ-value (a ratio of density to sensor output)and the gradation characteristics; those exerting the influences on eachof reading information obtained by reading images of the both sides ofthe original 9. Where images are printed on both sides of the paperprovided by the copying machine, it is preferable to equalize theprinting image quality of the one side to the one of the other side. Inorder to carry out this, it is necessary to agree the readinginformation of the upper image reader 10 a with the one of the lowerimage reader 10 b. Therefore, the copying machine is provided withreading correction means 12. Thereby it is arranged that each readingcharacteristics of the image readers 10 a and 10 b can be corrected andagree with each other.

[0055] For instance, regarding the above γ-value, the relation among thequantity of light (the total volume of light flux for a specific time)of the reflected light on the original 9, the output of a sensor 13 andthe γ-value is expressed by graphs of γ>1, γ=1 and γ<1 as shown in FIG.8. If the sensor output gets large at an arbitrary value a of quantityof light, the reading correction means 12 corrects the γ-value so as tobe γ>1. Likewise, the reading correction means 12 corrects the γ-valueso as to be γ=1 or γ<1, and then adjusts the values of the quantity oflight and the sensor output. Thereby, the both of reading information ofthe upper and lower image readers become the same one.

[0056] Besides, it may be arranged regarding the upper and lower imagereader 10 a and 10 b installed in the copying machine that the upperimage reader 10 a may be fixed, while the lower image reader 10 b may bemovable. The image reader may be movable adopting the fluorescent lightand the mirror like the conventional machine.

[0057] In this case, the processing of reading images is performed asfollows: first, the original 9 inserted in the original carrier 2 iscarried to a reading station 6 by the picking roller 31 and the feedingrollers 32 a and 32 b.

[0058] The original 9 is fed into the horizontal transport path 13 whilebeing read by the fixed type of image reader 10 a. On the lower side ofthe transport path 13 is a reading table (not shown in drawings) made ofglass placed. When the original 9 is positioned on the reading table,the belt roller 4 stops temporarily and the fluorescent light of thelight source (the reading position Pb as well as the light source) moveslike the way illustrated in FIG. 15. After the image reader 10 bcompletes the reading, the belt roller 4 starts and discharges theoriginal 9 outside.

[0059] Where the lower image reader 10 b is movable with the fluorescentlight and the mirror like the conventional copying machine, the original9 can be placed on the glass reading table. Thereby, the copying machinein the embodiment copes with the original that cannot be fed by theoriginal carrier 2.

[0060] It is needless to say that, instead of moving the lower imagereader 10 b using the fluorescent light and the mirror as above, whilethe fluorescent light may be fixed at a specific position, the readingmay be performed according to the original carried by the belt roller 4.

[0061] In addition, in order to avoid the big sizing of the copyingmachine and adopt the above configuration, the image reader must bedownsized. Therefore, it is preferable that the image reader shown inFIG. 2 is adopted in order to restrain the optical path length as muchas possible.

[0062] Specifically, the image reader comprises light receiving means 11a that is provided with lens 16 including a fiber lens 14 and the sensor13, and light source means 15 irradiating light on the original 9.

[0063] Since it is necessary to shorten the focal length of the fiberlens 14 and deepen the focal depth of it, the fiber lens 14 must consistof the optical fiber 140 with a fine diameter, e.g. 0.5 mm and less asshown in FIG. 3. Thereby, it is possible to shorten the focal length andrestrain the whole of the optical path length. On the contrary, thephenomena of the crosstalk and the flare become more and moreconspicuous. Therefore, it may be arranged that a light-absorbing layer143 be formed around individual optical fibers 140 of a specific lengthas shown in FIG. 5, or that a bundle of a plurality of optical fibers140 of a specific length, around which the light-absorbing layer 141 isformed, makes a fiber-bundle 144 as shown in FIG. 3. It is note that thefiber-bundle 144 may include the optical fiber 140 around which thelight-absorbing layer 143 is formed.

[0064] The fiber-bundle 144 is arranged to satisfy the followingrelation in order to prevent phenomena of the crosstalk and the flare.That is to say, as shown in FIG. 6, where one side length S of thefiber-bundle 144 is divided by the length T of the optical fiber 140,the value (S/T) is larger than the tangent value (tan ω) of the angularaperture ω that is the angle between the central axis U of the opticalfiber 140 and the incident light V. The outside diameter S, the length Tand the angular aperture ω are determined so as to satisfy the aboverelation.

[0065] A plurality of optical fibers 140 around which thelight-absorbing layer 143 is formed or a plurality of fiber-bundles 144around which the light-absorbing layer 143 is formed are stuffed with aspecific-shaped frame opening top and bottom sides, with a longitudinaldirection of the optical fiber 140 in the vertical direction and side byside in a diametrical direction of the optical fiber 140. And theadhesive is filled in the gaps among respective optical fibers 140,which is solidified. After that, the frame is removed. The specificshape of the frame is the one required by the copying machine or thescanner adopting the fiber lens 14 to offer the primary functions, andit generally takes a belt-shape having the length right-angled to thedirection of carrying the original. Moreover, if it is necessary for theshaping, after the individual optical fibers 140 or the fiber-bundles144 are held within the frame by basal plates 142 made of the opaqueglass or the resin as shown in FIG. 4, the basal plates 142 and theindividual optical fibers 140 or the fiber bundles 144 may be bonded toeach other according to the above-mentioned method.

[0066] In addition, there is the other method as follows (not shown inthe drawings). A plurality of optical fibers 140 around which thelight-absorbing layer 143 is formed or a plurality of fiber bundles 144around which the light-absorbing layer 143 is formed are disposed close,with the longitudinal direction of the optical fibers 140 in thevertical direction and side by side in a diametrical direction of theoptical fibers 140, and the adhesive is filled in the gaps among them.Moreover, they are put between basal plates 142 in a specific shape madeof the opaque glass or the resin and the adhesive is solidified by thethermo-compression bonding. Besides, the specific shape of the substrateis the same one as illustrated in FIG. 3 or FIG. 4.

[0067] The light source means 15 may be configured so that LED 150 ofLED element may be disposed close so as to be nearly in a belt shape,for example as shown in FIG. 7. Instead of the LED element, theconfiguration may be adopted so that the organic or inorganic electronicluminescence is formed almost in a belt shape.

[0068] The image reader 10 a (the image reader 10 b) is configured asthe light source configured as above is disposed symmetrically in theupward (downward) direction diagonal to the reading position Pa (thereading position Pb), while the fiber lens 14 is placed on the upward(downward) of the reading position Pa (the reading position Pb).

[0069] Regarding the optical fiber 140, the refractive index getssmaller gradually in the right angles of the axis to the periphery (forexample, get smaller according to the 2nd power of the increasingdistance). Accordingly, even if there is no light-absorbing layer 141and 143, the light is to be converged on the center in principle.Practically speaking, as the diameter gets small, the crosstalk and theflare phenomenon become more conspicuous. Therefore, the light-absorbinglayer 141 and 143 are needed.

[0070] The light-absorbing layer 141 and 143 may be formed by coating,dipping, or evaporating black resin on. The adhesive 145, which is usedfor filling in the frame stuffed with the individual optical fibers 140or the fiber-bundles 144, may be a conventional one, however it ispreferable that the resin is in black so as to prevent the crosstalk orthe flare phenomenon. The adhesive becomes the light-absorbing layer141. In this case, in order to make the black adhesive play a role ofthe light-absorbing layer, the individual optical fibers 140 or thefiber-bundles 144, on the periphery of which the adhesive is formed inadvance, is manufactured into the fiber lens 14 in the above-mentionedmethods of using the frame in a specific shape opening the top andbottom ends, or of the thermo-compression bonding while holding with twobasal plates 142. As a matter of course, under those manufacturingmethods, the black adhesive should cover all over the periphery of theindividual optical fibers 140 or the fiber-bundles 144. As the adhesive,the glass or the resin of which the softening point is low can be used,but the softening point must be lower than that of the materials of theoptical fiber 140 and the basal plates 142 constituting the fiber lens14.

[0071] By the way, where it is assumed that the optical fiber 140, whichthe fiber lens is provided with, be approximately 0.1 mm in diameterthat is one-sixth of the diameter of the conventional rod lens, and beapproximately 4.0 mm in length that is one-sixth of the length of theconventional rod lens, the image reader 10 a and 10 b becomesapproximate 10 mm in thickness of the vertical direction to the surfaceof the original 9, which is one-sixth of that of the conventionalcontact type of image reader.

[0072] Moreover, if a sensitive sensor is adopted as the sensor 13, itis possible to shorten the reading time by improving the reading speed.

[0073] Besides, the operations of the copying machine other than theabove description, for example, the operation that the image data readby the image reader 10 a and 10 b is printed on a paper included in thecopying machine, the carrying operation of the papers, and etc., arelike the prior art and not improved by this invention, so theexplanation will not described here.

[0074] By adopting the fiber lens as described above, it is possible toshorten the optical path length to that extent, however, LED array orelectronic luminescence must be adopted in order to downsize the deviceas described before. However, if the light source is like a fluorescentlight, the light intensity is large and the illumination width is wide,while in case of LED array or electronic luminescence, the lightintensity is small and the illumination width is narrow. Accordingly, asdescribed in the beginning, there is a problem that it is not possibleto obtain a sufficient image quality when the original shifts.

[0075] Therefore, the light source means 15 in the invention isconfigured as follows. That is to say, a slab lens 16 is pasted as acondensing lens on a light irradiation side of the belt-like lightsource 17 as shown in FIG. 9, thereby it is arranged a shown in FIG. 10Aso that the illuminance be uniformed at the irradiation position in themain-scanning and sub-scanning directions on the original surface,particularly within a specific field of the sub-scanning direction.

[0076] Thereupon, even if the shift of the original can be seen in thedirection away from the light source means 15, as far as the shift iswithin the specific field, it is possible to obtain the same illuminanceas that of the reading position Pa (the reading position Pb, in case ofthe lower side) as shown in FIG. 10B. And the image quality is notdeteriorated.

[0077]FIG. 11 shows the configuration of the light source means 15 inwhich the electronic luminescence is used as a luminescent medium 18.

[0078] As shown in FIG. 11, the slab lens 16 is pasted on one side ofthe glass substrate 21. Meanwhile, the electronic luminescence materialis evaporated or adhered to the other side of the glass substrate 21putting ITO (tin oxide) electrode 19 between them, and a sealingsubstrate 22 is pasted on the other side of the electro luminescencematerial putting a metal electrode 20 (aluminum electrode, for example)between them. The shape and refractive index of the slab lens 16 aredesigned so as to uniform the illuminance in the specific field on theoriginal as described above. Accordingly, those might be changeddepending on the angle and the distance made between the surface of theoriginal and the surface of the light source 17. The light source means15 concerned with this configuration may be almost in a shape of a beltas a whole and disposed at right angles to the direction of carrying theoriginal.

[0079]FIG. 12 shows a configuration for obtaining the color lightsources. Luminescence media R18, G18 and B18 corresponding to R(red),G(green) and B(blue) are disposed in order at specific intervals inlateral direction of the light source means 15, and close to each otherso as to form nearly a belt-like shape as a whole. The ITO electrode 19of the lens side is formed on each luminescence medium, while the metalelectrode 20 of the sealing substrate 22 is formed as a commonelectrode.

[0080] For instance, in case where the ITO electrode 19 comprises theITO electrode R19, G19 and B19 that are common to per each luminescencemedium R18, G18 and B18 and the metal electrode 20 is the commonelectrode, the sealing substrate 22 is provided with a terminal 24corresponding to the electrode R19, a terminal 25 to the electrode G19,a terminal 26 to the electrode B19, and a terminal 23 to the metalelectrode 20 respectively.

[0081] Although it is conceivable the luminescence medium 18 should beLED array besides the organic or inorganic electronic luminescence asdescribed above, even in this case, those must be disposed closely so asto be almost in a shape of a belt instead of disposing them per a singlearray at specific intervals like the prior art.

[0082]FIG. 13 shows a sectional view taken in the sub-scanning directionof the slab lens 16 formed in a preferable shape to uniform therefractive index.

[0083] The slab lens 16 shown in FIG. 13A is formed as a plane surfaceis placed on a position corresponding to a top of a curved surface of acylinder, the sectional view of which is in D-shape. In FIG. 13A, theplane surface is expressed by a straight-line 16 a, and provided atintervals of a distance 2L from the top of the curved surface. In FIG.13, the curved surface represented as a circular arc 16 b is a convex,and offers the working of the convex lens. On the whole, the convexplays a role of restraining the trapezoid-shaped distribution ofilluminance shown in FIG. 10, and forming the upper base of thetrapezoid-shaped distribution of illuminance by the plane surfacebetween the convexes.

[0084] The width W1 of the slab lens 16 depends on the width W0 of thelight source 17. This is because the light volume of the light source 17leaked from the side of the height L1, which is represented as thestraight-line 16 c in FIG. 13, is subjected to the influence of therelation between the width W1 of the slab lens 16 and the width W0 ofthe light source 17. At least, it is preferable that the width W1 of theslab lens 16 is larger than the width W0 of the light source 17. Theheight L1 of the side of the slab lens exerts the influence on themagnitude of the illuminance corresponding to the height of thetrapezoid. The more the height L1 increase, the more the illuminanceincreases and the narrower the distribution width of illuminance gets.On the contrary, the more the height L1 decreases, the more theilluminance decreases and the wider the distribution width ofilluminance gets. In addition, a radius R1 of the circular arc 16 b alsoexerts the influence upon the distribution of illuminance like theheight L1. Therefore, according to the estimated shifting volume of theoriginal and the required illuminance, the height L1 and the radius RIare adjusted.

[0085] The slab lens 16 shown in FIG. 13B is formed as a concave surfaceis placed on a position corresponding to a top of a curved surface of acylinder, the sectional view of which is in D-shape. This is differentfrom previous one in the shape of surface at the position, but otherparts is the same as the slab lens 16 shown in FIG. 13A. In FIG. 13B,the concave surface is expressed as a circular arc 16 d. The concavesurface among the convexes forms the upper base of the trapezoid-shapeddistribution of illuminance like the plane surface. A radius R2 of thecircular arc 16 d also exerts the influence upon the distribution ofilluminance.

[0086]FIG. 14 shows a concrete example of the actual distribution ofilluminance regarding the slab lens 16 shown in FIG. 13. In FIG. 14, thehorizontal axis shows a position in the sub-scanning direction, whilethe vertical axis shows the illuminance on the original surface. Thestraight line expresses the distribution of illuminance of the slab lens16 shown in FIG. 13A, and the dashed line expresses the distribution ofilluminance of the slab lens 16 shown in FIG. 13B. In addition, thedot-and-dashed line expresses the distribution of illuminance in case ofonly the light source 17, which the above cases are compared with.

[0087] As it is evident according to FIG. 14, two slab lenses 16 shownin FIG. 13 carries out the distribution of illuminance shaped intrapezoid.

[0088] As mentioned above, if the slab lens 16 is formed, for example,in a shape of a series of a convex, a plane or a concave, and a convexin the direction of the sub-scanning direction, it is possible to carryout the distribution of illuminance in a shape of trapezoid. In result,it is possible to prevent the deterioration of the image quality whenthe original shifts.

[0089] According to such configuration, it is possible to obtain theuniformed illuminance within the specific field on the original 9 byusing the electronic luminescence or LED with the relative small lightintensity and the narrow illumination width. And it is also possible toensure clear images against the shifting of the original 9.

[0090] Besides, though the above description refers to a case where theimage reader of the invention is applied to the copying machine, theimage reader can be applied also to the other devices such as afacsimile, a scanner, a multifunctional printer or the like. Inaddition, the image reader employing the above-mentioned slab lens 16may be provided to either one side of the transport path instead of boththe upper and lower sides.

INDUSTRIAL APPLICABILITY

[0091] As described above, the image processor of this invention isarranged that the image reader be provided to both the upper and lowersides of the transport path, so that it is possible to read at one timethe images drawn on both sides of the original. Accordingly, the imageprocessor needs not to be provided with the reversing roller and thelike. And the image processor can be downsized and the reading speed canbe improved. Therefore, the invention is available for the copyingmachine and the multifunctional printer that perform the both-sidesreading.

[0092] In addition, when the image reader uses the fiber lens of theinvention comprising optical fibers with fine diameter, it is possibleto shorten the optical path length and deepen the focal depth. The wholesize of the device can be smaller, and the image quality can beimproved. Moreover, it is possible to use the light source with smallconsumption electric power.

[0093] Further more, in case of the light source means of the invention,that is to say, even in a case of the light source with smallconsumption electric power wherein the light intensity is small and theillumination width is narrow, the discrepancy of the original causes thedeterioration of the image quality. Therefore, the light source means issuitable to a small-sized image processor.

1. An image reader comprising light source means for irradiating anoriginal surface with light and light receiving means for receivingreflected light on the original, in which the light receiving meanscomprises: a fiber lens which is provided with a light-absorbing layeraround at least one of individual optical fibers of a specific lengthdisposed in a specific shape and a fiber bundle bundling a plurality ofthe optical fibers.
 2. A fiber lens comprising a light-absorbing layeraround at least one of individual optical fibers of a specific lengthdisposed in a specific shape and a fiber-bundle bundling a plurality ofthe optical fibers.
 3. A fiber lens according to claim 2, wherein theindividual optical fibers have a distribution of a refractive index thatfalls down gradually in a direction right-angled to the axis of theoptical fiber.
 4. A fiber lens according to claim 2, wherein thefiber-bundle has a side length of the fiber-bundle, a length of theoptical fiber and an angular aperture that satisfy the relation that theside length of the fiber-bundle divided by the length of the opticalfiber is larger than a tangential value of the angular aperture of theoptical fiber.
 5. A method of manufacturing a fiber lens comprising thesteps of: stuffing a specific shaped frame opening top and bottom endswith one of individual optical fibers of a specific length and a fiberbundle bundling a plurality of the optical fibers around which alight-absorbing layer is formed, with a longitudinal direction of theoptical fiber in the vertical direction and side by side in adiametrical direction of the optical fiber; and solidifying an adhesivefilling gaps of the optical fibers.
 6. A method of manufacturing a fiberlens comprising the steps of: disposing close one of individual opticalfibers of a specific length and a fiber bundle bundling a plurality ofthe optical fibers around which a light-absorbing layer is formed, sideby side in a diametrical direction of the optical fiber; and solidifyingan adhesive filling gaps of the optical fibers by thermo-compressionbonding with disposed optical fibers put between two basal plates in aspecific shape.
 7. A method of manufacturing a fiber lens according toclaim 5 or 6, wherein the adhesive is used as the light-absorbing layer.8. A method of manufacturing a fiber lens according to claim 5 or 6,wherein the adhesive is either one of glass or resin that have a lowsoftening degree, and the softening degree is lower than that of thematerials composing the fiber lens.
 9. An image processor comprising animage reader including light source means irradiating an original andlight receiving means receiving reflected light on the original, whereinthe image readers are provided on upper and lower sides of a transportpath for the original.
 10. An image processor according to claim 9,wherein the image readers on the upper and lower sides are arranged soas to differ positions irradiated with light by the upper and lowerlight sources.
 11. An image processor according to claim 9, comprising:reading correction means for correcting a reading characteristics of theimage readers on the upper and lower sides so as to be the same.
 12. Animage processor according to claim 9, wherein the image readers on theupper and lower sides are fixed at specific positions respectively. 13.An image processor according to claim 9, wherein the image reader on theupper side is fixed at a specific position, while the other on the lowerside is movable.
 14. An image processor according to claim 9, in whichthe light receiving means comprises: a fiber lens which comprises anoptical fiber having a distribution of a refractive index that fallsdown gradually in a direction right-angled to the axis; and alight-absorbing layer formed around at least one of the individualoptical fibers of a specific length disposed in a specific shape and afiber-bundle bundling a plurality of the optical fibers.
 15. An imagereader comprising light source means irradiating an original surface andlight receiving means receiving reflected light on the original, whereinthe light source means uniforms the illuminance over a specific width ofthe main-scanning and the sub-scanning directions for reading images onthe original surface.
 16. An image reader comprising light source meansirradiating an original surface and light receiving means receivingreflected light on the original, in which the light source meanscomprises: a belt-like light source; and a condensing lens in a specificshape and with a specific refractive index attached to a irradiatingsurface of the light source.
 17. An image reader according to claim 16,wherein the condensing lens is in a shape of a series of a convex, oneof a concave and a plane, and a convex.
 18. An image reader according toclaim 17, wherein the condensing lens has a shape of a D-sectioncylinder of which one of a plane and a concave is placed on a positioncorresponding to a top of a curved surface.
 19. An image readeraccording to claim 15, in which the light receiving means comprises afiber lens which is provided with a light-absorbing layer around atleast one of individual optical fibers of a specific length disposed ina specific shape and a fiber-bundle bundling a plurality of the opticalfibers.
 20. An image processor wherein an image reader is placed on theupper and lower sides of a transport path respectively, said imagereader comprising light source means uniforms the illuminance over aspecific width of the main-scanning and the sub-scanning directions forreading images on the original surface and light receiving meansreceiving reflected light on the original.
 21. An image processorwherein an image reader is placed on either one of the upper and lowersides of a transport path, said image reader comprising light sourcemeans uniforming the illuminance over a specific width of themain-scanning and the sub-scanning directions for reading images on theoriginal surface and light receiving means receiving reflected light onthe original.
 22. An image processor according to claim 20 or claim 21,in which the light receiving means comprises a fiber lens which isprovided with a light-absorbing layer around at least one of individualoptical fibers of a specific length disposed in a specific shape and afiber-bundle bundling a plurality of the optical fibers.